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<p>North American pollution outflow is ubiquitous over the western North Atlantic Ocean, especially in winter, making this location a suitable natural laboratory for investigating the impact of precipitation on aerosol particles along air mass trajectories. We take advantage of observational data collected at Bermuda to seasonally assess the sensitivity of aerosol mass concentrations and volume size distributions to accumulated precipitation along trajectories (APT). The mass concentration of particulate matter with aerodynamic diameter less than 2.5 <span class="inline-formula">µm</span> normalized by the enhancement of carbon monoxide above background (PM<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M2" display="inline" overflow="scroll" dspmath="mathml"><mrow><msub><mi/><mn mathvariant="normal">2.5</mn></msub><mo>/</mo><mi mathvariant="normal">Δ</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="28pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="5ae6b0495bee251fbac1bfef6bb6209c"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-16121-2021-ie00001.svg" width="28pt" height="14pt" src="acp-21-16121-2021-ie00001.png"/></svg:svg></span></span>CO) at Bermuda was used to estimate the degree of aerosol loss during transport to Bermuda. Results for December–February (DJF) show that most trajectories come from North America and have the highest APTs, resulting in a significant reduction (by 53 %) in PM<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M3" display="inline" overflow="scroll" dspmath="mathml"><mrow><msub><mi/><mn mathvariant="normal">2.5</mn></msub><mo>/</mo><mi mathvariant="normal">Δ</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="28pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="c8fdc99ec2b4407938f2aa5aba123896"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-16121-2021-ie00002.svg" width="28pt" height="14pt" src="acp-21-16121-2021-ie00002.png"/></svg:svg></span></span>CO under high-APT conditions (<span class="inline-formula">&gt;</span> 13.5 mm) relative to low-APT conditions (<span class="inline-formula">&lt;</span> 0.9 mm). Moreover, PM<span class="inline-formula"><math xmlns="http://www.w3.org/1998/Math/MathML" id="M6" display="inline" overflow="scroll" dspmath="mathml"><mrow><msub><mi/><mn mathvariant="normal">2.5</mn></msub><mo>/</mo><mi mathvariant="normal">Δ</mi></mrow></math><span><svg:svg xmlns:svg="http://www.w3.org/2000/svg" width="28pt" height="14pt" class="svg-formula" dspmath="mathimg" md5hash="19fc9097c12ca03c91427d1cc7d7775a"><svg:image xmlns:xlink="http://www.w3.org/1999/xlink" xlink:href="acp-21-16121-2021-ie00003.svg" width="28pt" height="14pt" src="acp-21-16121-2021-ie00003.png"/></svg:svg></span></span>CO was most sensitive to increases in APT up to 5 mm (<span class="inline-formula">−</span>0.044 <span class="inline-formula">µg</span> m<span class="inline-formula">⁻³</span> ppbv<span class="inline-formula">⁻¹</span> mm<span class="inline-formula">⁻¹</span>) and less sensitive to increases in APT over 5 mm. While anthropogenic PM<span class="inline-formula">_2.5</span> constituents (e.g., black carbon, sulfate, organic carbon) decrease with high APT, sea salt, in contrast, was comparable between high- and low-APT conditions owing to enhanced local wind and sea salt emissions in high-APT conditions. The greater sensitivity of the fine-mode volume concentrations (versus coarse mode) to wet scavenging is evident from AErosol RObotic NETwork (AERONET) volume size distribution data. A combination of GEOS-Chem model simulations of the <span class="inline-formula">²¹⁰</span>Pb submicron aerosol tracer and its gaseous precursor <span class="inline-formula">²²²</span>Rn reveals that (i) surface aerosol particles at Bermuda are most impacted by wet scavenging in winter and spring (due to large-scale precipitation) with a maximum in March, whereas convective scavenging plays a substantial role in summer; and (ii) North American <span class="inline-formula">²²²</span>Rn tracer emissions contribute most to surface <span class="inline-formula">²¹⁰</span>Pb concentrations at Bermuda in winter (<span class="inline-formula">∼</span> 75 %–80 %), indicating that air masses arriving at Bermuda experience large-scale precipitation scavenging while traveling from North America. A case study flight from the ACTIVATE field campaign on 22 February 2020 reveals a significant reduction in aerosol number and volume concentrations during air mass transport off the US East Coast associated with increased cloud fraction and precipitation. These results highlight the sensitivity of remote marine boundary layer aerosol characteristics<span id="page16122"/> to precipitation along trajectories, especially when the air mass source is continental outflow from polluted regions like the US East Coast.</p>